1. Field of the Invention
The invention generally relates to hairsetters used to heat one or more hair rollers to a predetermined temperature for use in setting hair. More particularly, the invention relates to a new electrical hairsetter and roller system having an electrical connecting system for supplying power to electrical heating elements within each hair roller.
2. Description of the Prior Art
Hairsetters are used to heat a plurality of hair rollers to a predetermined temperature. There are generally two types of hairsetters each depending upon the type of roller to be used. One type of hairsetter is shown in U.S. Pat. No. 3,858,029, assigned to the assignee hereof, showing a plurality of heated mounting posts, each for supporting one roller. The posts are heated by thermal conduction from a common base plate heated by a resistance wire heater. Examples of rollers which may be used with such a hairsetter are shown in U.S. Pat. Nos. 4,202,360; 3,773,057 and Re. 26,766, all assigned to the assignee hereof. Such rollers comprise a cylindrical shell having an external, hair winding portion and may be provided with a cylindrical casing concentrically aligned with the external hair winding portion and containing a heat retaining material for keeping the roller heated during use.
Another type of hairsetter and roller combination is shown in U.S. Pat. No. 4,447,705, assigned to the assignee hereof. This patent shows a roller heated by a transversely situated positive temperature coefficient (PTC) material which receives electrical power through an axial contact pin operating in conjunction with one concentric contact to complete the circuit. Such a roller requires a hairsetter having a centrally apertured socket for receiving the contact pin and its concentric contact as shown in FIG. 10 of the aforementioned U.S. Pat. No. 4,447,705. Hair rollers heated by internal PTC elements reach their operating temperature more quickly and efficiently than those heated through mounting posts. However, hair rollers using the aforementioned transverse PTC elements are generally expensive and, because of the unusual shape of the roller body, can only be molded with low temperature material. Thus, the heat available with such rollers is lower than it should be for efficient hair curling.
In view of the above, an axially aligned PTC element sandwiched between opposing electrically and thermally conductive heat sinks would enable rapid and efficient thermal distribution to the hair winding portion. Such a construction, albeit not in a hair roller, is generally shown in U.S. Pat. No. 4,147,927. However, there is no suggestion in this patent, or in the prior art of which Applicants are aware, of how to embody such an axially aligned structure in a hair roller which may be easily engaged and disengaged from a hairsetter base.
Accordingly, it is an object of this invention to provide a hair roller having an electrically insulated hair winding portion and utilizing an axially aligned PTC heating element situated between opposing electrically and thermally conductive heat sinks. It is a further object of this invention to produce such a PTC hair roller having electrical plug members integrally formed into the ends of said heat sinks. It is also an object of this invention to provide a hairsetter having at least one socket member for receiving such a PTC hair roller. It is yet another object of this invention to provide an electrical connecting system for use in such a PTC roller/hairsetter combination wherein the roller may be easily mounted as needed. It is an additional object of this invention to provide a hairsetter capable of being manufactured with relatively less flame retardant, and therefore lower cost material than prior art hairsetters. It is also an object of this invention to provide a hairsetter which utilizes an electrical connecting system which minimizes wear of contacts.